The present invention relates to a check valve for nominal width over 50 mm.
Check valves of the above mentioned general type are known in the art. In a known check valve, disclosed for example in U.S. Pat. No. 2,344,041, the intermediate housing part is composed of an essentially tubular or hollow-cylindrical parts by a fillet weld joint. One of the short connecting pipes forms an integral component of the cylindrical intermediate part, and the opposite connecting pipe is welded on the intermediate part by a ring-shaped fillet seam, so that the weld seam serves simultaneously for fixing the bottom part of the pipe band inside the housing. In the region of the upper housing opening for the passage of the valve spindle or in the region of the closing body connected therewith and cooperating with the seat ring of the pipe band, a ring pipe surrounding the housing opening is welded by a further fillet seam. The ring pipe serves in turn for connecting with the cover part of the valve.
The advantage of this check valve is that the connecting pipe in direction of the common throughflow axis can be dimensioned relatively shorter than the known check valves, on the one hand, and the utilization of the angular pipe band as a carrier for the seat ring provides for favorable flow conditions during conveyance of the medium from the supply side to the discharge side, on the other hand.
However, this check valve has substantial disadvantage in that its complicated construction requires expensive and not easily automatable manufacture, and that the intermediate housing part assembly from tubular and hollow-cylindrical parts does not provide for favorable relation between material consumption and housing dimensions, on the one hand, and strength, on the other hand. The strength means here both the pressure strength against the inner pressure from the medium and also the deformation resistance of the intermediate housing part against pulling and pressing loads acting from above via the connecting conduit directly onto the intermediate housing part.
It is to be understood that the above mentioned disadvantages increase with increase of the nominal width, for which the check valve must be designed.
For providing favorable relation between material consumption, space utilization and strength, it is generally known in armatures to form the intermediate housing part with a hollow circle shape and composed of two identical half shells with integrated connecting pipes, which are connected by welding along a central plane which is normal to the throughflow axis. This is disclosed, for example, in the DE-AS No. 2,725,799. It is also known to use non-spherical intermediate housing parts for armatures which are assembled of drop-forged parts, as disclosed for example in DE-PS No. 912,649 or DE-Gm No. 1,706,081
In all these cases, there is however an intermediate housing part for a check slider which, because of its fully symmetrical interior construction, is rather suitable as an intermediate housing part for a check valve with its functionally required asymmetrical inner construction.